Fuel cell system

Abstract

A fuel cell system includes a fuel cell, a water storage unit configured to store water recovered from the fuel cell and be able to drain the stored water, a water usage unit configured to use the water in the water storage unit, and a control unit configured to control a drain of the water from the water storage unit. The control unit is configured to, when a first predetermined time has elapsed since a last drain of the water from the water storage unit, drain the water from the water storage unit. The control unit is configured to, when it is predicted that the water in the water storage unit is used by the water usage unit within a second predetermined time shorter than the first predetermined time, not drain the water from the water storage unit even when the first predetermined time has elapsed since the drain of the water from the water storage unit.

What is claimed is: 
     
       1. A fuel cell system comprising:
 a fuel cell configured to cause an electrochemical reaction between hydrogen and oxygen, the fuel cell being configured to produce water as a result of the electrochemical reaction; 
 a water storage unit configured to store the water recovered from the fuel cell, the water storage unit being configured to be able to drain the stored water; 
 a water usage unit configured to use the water in the water storage unit; and 
 a control unit configured to control a drain of the water from the water storage unit, the control unit being configured to
 when a first predetermined time has elapsed since a last drain of the water from the water storage unit and it is predicted that the water is not used by the water usage unit within a second predetermined time shorter than the first predetermined time, drain the water from the water storage unit, and 
 when the first predetermined time has elapsed since the last drain of the water from the water storage unit and it is predicted that the water is used by the water usage unit within the second predetermined time shorter than the first predetermined time, not drain the water from the water storage unit even when the first predetermined time has elapsed since the drain of the water from the water storage unit. 
 
 
     
     
       2. The fuel cell system according to  claim 1 , further comprising
 a heat exchanger configured to release heat generated in the fuel cell to an outside of the system; and 
 a temperature detection unit configured to detect a temperature of the heat exchanger, 
 wherein the control unit is configured to, when the first predetermined time has elapsed since the drain of the water from the water storage unit and the temperature of the heat exchanger is lower than a predetermined value, restrict the drain of the water from the water storage unit. 
 
     
     
       3. The fuel cell system according to  claim 2 , wherein the control unit is configured to, when the first predetermined time has elapsed since the drain of the water from the water storage unit and the temperature of the heat exchanger is lower than the predetermined value, not drain the water from the water storage unit. 
     
     
       4. The fuel cell system according to  claim 2 , wherein the control unit is configured to drain the water from the water storage unit at a first flow rate when the first predetermined time has elapsed since the drain of the water from the water storage unit and the temperature of the heat exchanger is lower than the predetermined value, the first flow rate being lower than a second flow rate at which the water is drained from the water storage unit when the first predetermined time has elapsed since the drain of the water from the water storage unit and the temperature of the heat exchanger is higher than or equal to the predetermined value. 
     
     
       5. The fuel cell system according to  claim 4 , wherein the control unit is configured to, when the first predetermined time has elapsed since the drain of the water from the water storage unit and the temperature of the heat exchanger is lower than the predetermined value, drain the water from the water storage unit at the first flow rate when a third predetermined time longer than the first predetermined time has elapsed since the drain of the water from the water storage unit. 
     
     
       6. The fuel cell system according to  claim 1 , further comprising a heat exchanger configured to release heat generated in the fuel cell to an outside of the system, wherein:
 the water usage unit is a spray unit configured to spray the water in the water storage unit on the fuel cell to cool the heat exchanger with latent heat of vaporization of the water; and 
 the control unit is configured to predict an operation condition of the fuel cell within the second predetermined time, and determine whether to spray the water in the water storage unit on the heat exchanger with the spray unit within the second predetermined time based on the predicted operation condition of the fuel cell. 
 
     
     
       7. The fuel cell system according to  claim 6 , further comprising a temperature detection unit configured to detect a temperature of the heat exchanger, wherein the control unit is configured to, when the first predetermined time has elapsed since the drain of the water from the water storage unit and the temperature of the heat exchanger is lower than a predetermined value, restrict the drain of the water from the water storage unit. 
     
     
       8. The fuel cell system according to  claim 1 , wherein the water is drained from the water storage unit as the water is used by the water usage unit. 
     
     
       9. A fuel cell system comprising:
 a fuel cell configured to cause an electrochemical reaction between hydrogen and oxygen, the fuel cell being configured to produce water as a result of the electrochemical reaction; 
 a water storage unit configured to store the water recovered from the fuel cell, the water storage unit being configured to be able to drain the stored water; 
 a heat exchanger configured to release heat generated in the fuel cell to an outside of the system; 
 a temperature detection unit configured to detect a temperature of the heat exchanger; and 
 a control unit configured to control a drain of the water from the water storage unit, the control unit being configured to, when a first predetermined time has elapsed since a last drain of the water from the water storage unit and the temperature of the heat exchanger is higher than or equal to a predetermined value, drain the water from the water storage unit, and, when the first predetermined time has elapsed since the last drain of the water from the water storage unit and the temperature of the heat exchanger is lower than the predetermined value, restrict the drain of the water from the water storage unit. 
 
     
     
       10. The fuel cell system according to  claim 9 , wherein the control unit is configured to, when the first predetermined time has elapsed since the drain of the water from the water storage unit and the temperature of the heat exchanger is lower than the predetermined value, not drain the water from the water storage unit. 
     
     
       11. The fuel cell system according to  claim 9 , wherein the control unit is configured to drain the water from the water storage unit at a first flow rate when the first predetermined time has elapsed since the drain of the water from the water storage unit and the temperature of the heat exchanger is lower than the predetermined value, the first flow rate being lower than a second flow rate at which the water is drained from the water storage unit when the first predetermined time has elapsed since the drain of the water from the water storage unit and the temperature of the heat exchanger is higher than or equal to the predetermined value. 
     
     
       12. The fuel cell system according to  claim 11 , wherein the control unit is configured to, when the first predetermined time has elapsed since the drain of the water from the water storage unit and the temperature of the heat exchanger is lower than the predetermined value, drain the water from the water storage unit at the first flow rate when a third predetermined time longer than the first predetermined time has elapsed since the drain of the water from the water storage unit.